The invention relates to flexible shaft couplings of the tubularly-shaped, yielding element type, but more particularly, the invention relates to a sporadical torque transferring device that enhances performance of a tubularly-shaped, yielding element type flexible shaft coupling.
Some yielding element type flexible shaft couplings are useful for attenuating certain noise and vibration in some rotary, articulated shaft systems. Examples of such flexible elements appear in U.S. Pat. Nos. 3,628,352; 3,855,817; 3,347,061; and 3,621,674. Apparatus for attaching such yielding element couplings to rotary shafting are shown in U.S. Pat. Nos. 3,788,098; and 3,973,411. While such couplings are suitable for such vibration and noise attenuating service, the couplings do not give suitable warning for impending failure; are susceptible to buckling failure at infrequent torque overloads; and are incapable of transferring torque for a discrete warning period before an impending failure.